Tires are conventionally provided with colored layers (orh painted layers) to place decorations and the like on the outer surfaces of the side portions. Such tires, now being widely available, include non-staining or slightly-staining sidewall innerlayer rubbers, which do not contain staining antioxidants, to prevent the decorative parts from being stained by the antioxidants contained in the surrounding rubber. Refer to JP H4-121205 (PTL 1). This technique conventionally known in the art allows the decorative parts to be disposed apart from the black rubber layer that contains antioxidants.
Coloring on tires, such as surface painting and printing, has been also widely performed to improve decorativeness or visibility of tires. In such coloring, although a heat-curable or a solvent-volatiling paint has been generally used, an ultraviolet (UV) curable paint are now being widely used. This is because the UV-curable paint cures much more rapidly than the heat-curable or solvent-volatilizing painting and requires less amount of organic solvent and no heat in curing to be less likely to cause quality changes in the based material. For example, JP 2010-125440 A (PTL 2) discloses a method of decorating tires using a UV-curable ink. JP 2004-526814 (PTL 3) and JP 2009-520616 (PTL 4) disclose a tire having a colored layer made of a polyurethane layer on its sidewall. As mentioned above, rubber members disposed on the outer surface of a tire, such as a sidewall, generally contain antioxidants and the like to prevent the degradation caused by ozone or UV light. It is known that such antioxidants gradually migrate toward the tire surface over time as the tire is used.
Tires are also conventionally provided with markings such as corporate name, brand name, tire size, the date of manufacture, etc. that are placed on the outer surfaces of their side portions, i.e., the outer surfaces of their sidewalls and beads. The markings may include character(s), figure(s), sign(s) including bar codes, pattern(s) or any combination thereof. Refer for example to JP 2010-100090 A (PTL 5). Such markings are placed on the surface of the tire by printing or painting, by attaching a decorated seal, or by exposing an embedded colored rubber. In typical tires, which are black in their base color, markings are imprinted in white color on the black background. Because the surface of the side portion of tire tends to become dirty, the white markings on the black background may become less visible as the tire is used. In addition, there is a demand for stimulating purchasing interest by emphasizing the markings of unused, new tires. To satisfy such a demand, coloring on marking portions has been proposed for example by PTLs 2, 3, and 4. PTL 2 discloses a method for printing markings on tires by using UV-curable ink, and PTLs 3 and 4 propose providing a colored layer made of polyurethane on the sidewall of a tire.